mPEG-CHO

mPEG-CHO AffiPEG is a chemically modified form of methoxy polyethylene glycol (mPEG) that features a terminal aldehyde (–CHO) functional group. This design allows mPEG-CHO to react with nucleophilic groups—most notably primary amines—on proteins or other biomolecules, facilitating site-specific conjugation.

Content and Chemical Characteristics

• Chemical Structure: The molecule consists of a methoxy-terminated polyethylene glycol chain with a molecular weight that can vary depending on the application (commonly from 2 kDa up to 40 kDa), ending in an aldehyde functional group. The general formula can be represented as CH₃(OCH₂CH₂)_nCHO, where “n” determines the chain length and thus the molecular weight.
• Reactivity: The aldehyde group at one end of the PEG chain is reactive towards primary amines via Schiff base formation. Under controlled conditions (typically mildly acidic to neutral pH), the aldehyde reacts with the ε-amino groups of lysine residues on proteins or N-terminal amines, forming an imine (Schiff base).
• Conjugation Conditions:
  • pH: Reactions are usually conducted at pH 5.0–7.5 to balance the nucleophilicity of the amine and the electrophilicity of the aldehyde.
  • Temperature: Ambient to slightly elevated temperatures (e.g., 20–37°C) are used to facilitate the reaction kinetics without denaturing sensitive biomolecules.
  • Stoichiometry: The molar ratio of mPEG-CHO to target molecules is optimized to control the degree of PEGylation, often aiming for mono-PEGylation to preserve biological activity.

Applications of mPEG-CHO AffiPEG

• Protein PEGylation:
  • Stability and Solubility: Conjugation with mPEG-CHO imparts increased solubility and stability to proteins by shielding them from proteases and reducing aggregation.
  • Pharmacokinetics Enhancement: PEGylated therapeutic proteins often exhibit prolonged circulation times and reduced immunogenicity, leading to improved drug profiles.
• Affinity-Based Conjugation and Purification:
  • Targeted Attachment: In an AffiPEG approach, the PEG chain can be combined with affinity ligands (e.g., antibodies, aptamers, or specific binding peptides) to selectively capture or immobilize target proteins on PEG-modified surfaces.
  • Chromatography Matrices: mPEG-CHO derivatives can be immobilized on solid supports to create affinity chromatography columns, where the aldehyde’s reactivity ensures robust attachment of affinity ligands that capture specific analytes from complex mixtures.

mPEG-CHO AffiPEG serves as a versatile reagent in biochemical engineering, combining the benefits of PEGylation—such as increased solubility, reduced immunogenicity, and improved stability—with affinity-based strategies for targeted conjugation and purification. Its reactivity under mild conditions preserves biomolecule functionality while enabling the construction of advanced biomaterials, therapeutic agents, and diagnostic tools.